The present invention relates to integrated circuits. More specifically, the present invention is directed at configuring a PLD having embedded logic.
A programmable logic device (PLD) is an integrated circuit, which can be customized by a system designer to perform different logical functions. PLDs combine the advantages of fixed integrated circuits with the flexibility of custom integrated circuits. By using these devices, custom logic functions can be designed and fabricated in-house, while eliminating long engineering lead times, high tooling costs, and dedicated inventory problems associated with custom devices. Furthermore, the design can be easily changed without upsetting design schedules and purchase agreements.
PLDs often comprise a plurality of generic logic blocks that may be arbitrarily programmed and interconnected to each other. These blocks may be implemented using volatile memory such as static random access memory (SRAM) or, alternatively, with nonvolatile memory such as erasable programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), fuses, and antifuses. If the programmable elements are volatile memories, the memory cells must be configured upon system power-up in order for the device to operate as desired. This is typically done by loading configuration data from an external configuration source into the PLD. The configuration source may be, for example, a nonvolatile memory such as a FLASH memory. Configuration of the PLD is accomplished by transferring the configuration data from the configuration source to the PLD.
Recently, there has been a trend to embed other logic devices such as within a PLD. Embedded devices (i.e. “embedded logic”) may comprise control logic and other application specific logic devices such as, volatile memory, non-volatile memory, cache, etc. and are embedded prior to configuration of the programmable logic core. A processor (or central processing unit CPU)) may also comprise part of the embedded logic. A processor is an integrated circuit implemented on a semiconductor chip, which typically includes, among other things, an instruction execution unit, register file, arithmetic logic unit (ALU), multiplier, etc. Processors are found in digital systems, such as personal computers for executing instructions, and can also be employed to control the operation of most digital devices.
While the addition of embedded logic has proven to be desirable, there remains a need of a method for setting up (i.e., configuring) embedded logic devices, in addition to configuring the PLD core.